For a long period of years roofs were covered by applying multiple layers of material with at least one of those layers usually being a moisture resistant material such as a felt material soaked in bitumin. To prevent the wind from tearing away the layers of the roofing material, gravel was often used to hold down the multiple layers.
Recent advances, especially in the material manufacturing area, have led to the development of a number of new approaches to applying roofing material. One which has gained considerable acceptance, due mostly to its ease of application, is the single ply roofing system. The single ply roofing system involves the covering of a roof substrate with one or more layers of a membrane of a suitable elastomeric material such as neoprene, polyvinyl chloride, ethylene propylene diene monomer or the like. Multiple ply membranes of different materials or of a single material may also be used. Roofing membranes of this type are generally manufactured in large sheets ranging from 3 to 40 feet in width and in lengths of up to 125 feet or more. For ease in shipping and subsequent application the sheets are generally sold in rolls.
In applying a roofing membrane to a roof substrate, two areas are of great concern, namely preventing water leakage through the membrane to the substrate below and preventing wind forces from tearing the membrane off the underlying substrate.
Securement of the roofing membrane to an underlying substrate, which can be any type of material such as sheet metal, cork board, insulation board, concrete or the like, can be accomplished in several different ways, for instance, the ballast method involving utilizing stones to weight the membrane down or an adherence method which involves applying an adhesive to the substrate and rolling out sheets of the roofing membrane over the adhering substrate. The ballast method and the adherence method, however, present difficulties when it is desired to replace a worn roofing membrane with a new one. Both the adherence system and ballast system involve substantial labor and material costs each time an old membrane is to be replaced with a new membrane.
Alternatively, a partially attached system may be utilized whereby a number of anchoring or securement devices secure the membrane to the substrate at a number of different points. If the securement devices are made so as to be easily detachable and reusable, extensive labor and material cost savings can be achieved. However, the use of a partially attached or point attachment system presents a number of problems itself. For example, the point attachment system, unlike the ballast or adhesive system, secures the roofing membrane to the roof substrate at a number of isolated points rather than over the entire surface area of the membrane and/or substrate. In high wind areas this can present a problem, since prevention of wind damage requires that the points of attachment be concentrated to such an extent as to make the use of such a system impractical.
Another problem associated with a point attachment system arises when the particular system involves a fastener which penetrates the membrane. Penetration of the membrane creates a location where leakage can occur, and, to compensate, additional labor and materials are required for sealing off the area of leakage, thus making the use of such a system economically impractical.
To achieve the possible advantages the point attachment system has over other systems in ease of roof membrane application and removal and reusable securement means, it is necessary that the foregoing problems be dealt with. The labor costs can be reduced by utilization of a securement means which can be easily inserted or assembled and withdrawn or disassembled and by avoiding penetration of the roofing membrane. Material costs can be greatly reduced if the securement means can be used over and over again without loss of its securement power. To achieve both a labor cost reduction and a material cost reduction has proven to be difficult in that generally the reduction of labor costs is brought about by factors resulting in a corresponding rise in material cost, or vice versa. To develop a securement means which can be repeatedly reused requires that the material of which it is made be capable of withstanding extreme weather and temperature variations while at the same time retaining its fastening strength even after repeated insertions or withdrawals.
Francovitch U.S. Pat. No. 4,520,606 illustrates various embodiments of roofing membrane anchors. FIGS. 1-4 of the Francovitch patent depict anchoring systems each having a linear fastener extending through the membrane. As previously discussed, such systems result in undesirable labor costs, as the point of penetration must be sealed to prevent leakage.
FIGS. 5-9 of the Francovitch patent show a solution to the problem of increased labor cost due to sealing requirement. In these figures various embodiments of head and socket arrangements are illustrated which do not require roofing membrane penetration. However, the locking components are formed of either a resilient plastic or a rubber material, each of which is susceptible to deterioration over extended periods of time in extreme weather conditions, such as extreme heat and extreme cold, as experienced over a number of years. This deterioration results in the locking members losing their fastening powers or in cracks developing, especially after repeated bendings due to assembly and disassembly. Also, during assembly and disassembly the type of material used is readily susceptible to damages caused by a workman's tool or the like.
Francovitch's FIG. 10 reveal yet another roofing membrane anchoring system which utilizes an upper plate element, including a key portion, and a lower plate having a notch in it. Securement of the two plates with the roofing membrane therebetween is achieved by placing the key portion in the notch and rotating the upper plate until the key lies beneath a shoulder of the lower plate. This system requires the use of a tool to rotate the upper plate and thus requires increased capital expenditure and labor to insert the tool and rotate the upper plate. Moreover, the system fails to provide a sufficiently secure locking system, as vibrations or other naturally occurring events may cause the upper plate to rotate to the unlocked position.